Synthesis, spectroscopic characterization, and photophysical properties of new p -anisolylthiol-functionalized platinum(II) bis(alkenylarylalkynyl) complexes

A series of organic sulfur-functionalized trans -platinum(II) bis(alkenylarylalkynyl) complexes, having one anisolylthio group with general formula trans -[(PEt 3 ) 2 Pt{C≡C–Ar–CH=CH(SC 6 H 4 –OCH 3 )} 2 ], (2a-2d) , (Ar = phenylene/biphenylene/2,5-dimethylphenylene/2,5-dimethoxyphenylene) was synthesized in excellent yields. All the new platinum(II) complexes have been fully characterized by physico-chemical and spectroscopic methods. Photophysical properties of the complexes were studied by absorption and emission spectroscopy. The lowest energy absorption band for the complexes, in the UV/Vis spectra, in THF solution, at room temperature, 2a-2d was observed in the range 355–391 nm, which depend on the spacers in the acetylide ligand e.g., the absorption of 2d is red shifted to 391 nm for the donor (OCH 3 ) substituents in phenyl spacer. These absorptions originated predominantly from π–π*orbitals of acetylide ligand with significant contribution from the platinum dπ orbital as evident from the HOMO and LUMO, obtained from TD-DFT calculations. Fluorescence was observed in all complexes at room temperature in the range 400–428 nm with PLQY of 2–5%. At 77 k, the complexes 2a-2b only exhibited phosphorescence in the range 579–585 nm, but there is no phosphorescence at ambient temperature. Graphical abstract